Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users may see that composed text is rendered in a different font once sent in Microsoft Teams – RESOLVED

Announcements Arpan Das

17/10/2025 08:51:00 AM

NHSmail Reference: INC46658703

Microsoft Reference: TM1173754

Issue Status: ONGOING

Issue Description: Users may see that composed text is rendered in a different font once sent in Microsoft Teams

More info: Users report that impact is occurring on the Microsoft Teams web client (Version: 25227.203.3915.2444) and the desktop client (Version: 25255.703.3978.7153).

Impact seems to be specific to text using SimSun fonts.

Final Update: 17/11/2025 09:16:00 AM – Microsoft have confirmed their fix deployment saturated across the entire affected infrastructure and remediated impact.

Scope of impact: Any user sending SimSun font text from Microsoft Teams web client version 25227.203.3915.2444 and desktop client version 25255.703.3978.7153 may be affected.

Root cause: A recent service update to facilitate additional fonts contains a code error causing Microsoft Teams to incorrectly assign the font, resulting in impact

Next Steps: Microsoft are reviewing their service update processes to better inform how we can detect code errors and prevent similar incidents from occurring in the future.